A transistor in which a physical property of its channel is changed according to an applied voltage, and methods of manufacturing and operating the same are provided. The transistor may include a first conductive layer on a substrate, a phase change layer and a second conductive layer which are sequentially stacked on the first conductive layer, a first current direction limiting unit and a second current direction limiting unit formed on the second conductive layer by being separated within a space, a third conductive layer and a fourth conductive layer formed on the first current direction limiting unit and the second current direction limiting unit, respectively, a word line connected to the third conductive layer, a bit line connected to the fourth conductive layer, and a voltage lowering unit connected to the word line.